The invention relates to an ironing ring for use in a press for ironing pressing of a workpiece.
Such ironing rings have been known per se. In a press for ironing pressing or drawing a workpiece, for example a cup, several such ironing rings are successively arranged, as a rule, in the direction of the working stroke in order to intermittently or incrementally reduce the outside diameter of the workpiece. As a result of this, it is possible, for example, to ultimately form a hollow cylindrical can body from a cup.
During the deforming process, a radially inward facing work surface of the ironing ring comes into contact with the workpiece. Depending on the material of the workpiece, more or less viscous, smeary material build-up or friction deposits occurs. This phenomenon is known. Nowadays, the ironing rings are therefore deinstalled from the press after a certain number of deforming processes, cleaned and subsequently reinstalled. This is labor-intensive and expensive and has caused the shutdown of the press.
In order to avoid friction deposits, publication DE 22 56 334 A1 discloses the possibility of applying a special lubricant to the ironing ring or the workpiece. However, such lubricants must subsequently be removed again from the deformed workpiece. This option is labor-intensive and expensive as well. Publication DE 22 56 334 A1 suggests that the ironing ring be made of ceramic material. However, if pressure is suddenly removed from the ceramic ironing ring, fissures may form, this being prevented according to DE 22 56 334 A1 in that the end region of the workpiece may immerse into a recess on the ironing stamp in order to avoid the sudden removal of pressure from the ceramic ironing ring.
Considering this, the object of the present invention may be viewed to be an ironing ring in which the risk of friction deposits is reduced and which does not require any design changes on other press components.